Ceisum JS White Screen

Hi Cesium Community,

I want to use Cesium to verify the geo-location of my Ifc file which came from my Autodesk Revit model. A tool/program has been developed already for this purpose called ifcLocator:

I used python to create a local server but after launching there is a white screen (screenshot below) and no map imagery in loaded. Do you know why or how can i solve the problem?